The Ba'al HaTurim to Deut. 11:26 cites Bab. Megillah 31b in saying that all the blessings and curses in "Mishneh Torah" (usually this means Sefer Devarim - Deuteronomy) are written in singular, and says that, therefore, "some explain" that that's why ReEh in Deut. 11:26 is singular.
First, who are the "some"?
Second, this is clearly not the case. For example, Deut. 4:15-18 is clearly a dire warning and curse against anyone who worships idols, yet it is in plural language. What do the commentaries say about this Gemara that the Ba'al HaTurim cites?